[Mike O]

No, that got the message across well. Thx also 12 piece for your valued comments.

2-C-1 shows separation occurring at the Low Point, where the clubface is square to the Plane Line.

When the Low Point occurs 3 or so inches after the (up-plane) point of Separation, I assume Low Point is still where the clubface becomes square to the Plane Line with a 10-5-A Square-Square alignment - is that correct?

So at Impact Fix, the clubface is set up open for a 10-5-A alignment, the degree of 'openness' depending on the rate of closure of the selected hinging and the chosen release?

There is no relevant correlation between clubface alignment and lowpoint.
Sure in the "Golfing Machine book" because of "that" machine and for simplicity sake - separation is at lowpoint. In the "real" world- while that's possible- normally I would say that separation is well before lowpoint- as you have stated above. In that case you want the face square to your initial starting direction of the ball at separation. Swingvision will provide some good information on impact conditions for you but assuming the face is closing then yes the openess at impact fix would be based on A) the rate of closure of the selected hinging and B) the amount of compression i.e. the more the compression the more the face closes due to the longer period of closing before the ball leaps off the face.